External tubing can greatly impact a receivers response curve. Varying the tubing length, varying the tubing diameter, using combinations of different tubing lengths/diameter, and adding acoustic dampers can all have a marked impact on receiver output.

The impedance of the signal source with respect to the receiver's impedance can affect the shape of the response curve. The impact of source impedance vs. receiver impedance matching is presented for constant current, constant voltage, and maximum available power drives.